Conventionally, an in-vehicle information terminal such as an in-vehicle navigation device has a HMI (i.e., human machine interface) with using a voice recognition process in the terminal so that safety and convenience are improved.
Alternatively, the terminal having the voice recognition function includes a communication element so that the terminal is coupled with an external center via the communication element. The voice recognition process is executed by the external center, and the terminal can search information with using the voice recognition process in the external center. This voice recognition process in the external center is defined as center side voice recognition process. This technique is described in Japanese Patent No. 3862169.
Here, in the voice recognition process, the number of words, which is audibly perceptive, and the structure of a sentence, which is recognizable, depend on a computer capacity since it is necessary to execute a large amount of calculations and to use a large amount of memory.
Thus, since the computer capacity of a calculation processor in an in-vehicle information terminal such as an in-vehicle navigation device is comparatively low, the voice recognition is limited to address recognition and/or comparatively easy word recognition and the like.
On the other hand, in the center side voice recognition process executed by an external center, the computer capacity of a calculation processor in the center is high, so that the number of recognizable words is large, and the comparatively complicated structure of the sentence is recognizable.
Thus, the category and the number of recognizable words, the structure of the recognizable sentence, and the purpose of the voice recognition in the local voice recognition process are different from those in the center side voice recognition process. Accordingly, when the in-vehicle terminal can utilize the local voice recognition process and the center side voice recognition process, it is necessary for the user to select one of the local voice recognition process and the center side voice recognition process.
However, in a conventional in-vehicle information terminal, when the user outputs a voice in order to utilize the voice recognition function, the user cannot easily distinguish which of the local voice recognition process or the center side voice recognition process is executed. Thus, the user cannot output the voice with distinguishing between the local voice recognition process and the center side voice recognition process.
For example, in the navigation device, when the user operates a switch such as a telephone number search switch, an address search switch, a facility search switch and the like according to a menu screen, the navigation device starts to execute the local voice recognition process. When the user operates a switch such as an information search switch, a news presenting switch and the like according to the menu screen, the navigation device starts to execute the center side voice recognition process. In this case, unless the user outputs the voice with distinguishing between the local voice recognition process and the center side voice recognition process, the navigation device may start to perform a unintended operation.
For example, when the navigation device executes the center side voice recognition process, and the user says “a good hamburger shop in Tokyo,” the phrase of “a good hamburger shop in Tokyo” is recognized, and then, the navigation device displays search results of “a good hamburger shop in Tokyo.” However, when the navigation device executes the local voice recognition process, and the user says “a good hamburger shop in Tokyo,” the navigation device may not recognize the phrase of “a good hamburger shop in Tokyo” accurately. For example, the navigation device may mistake to recognize “a sandwich bar near the vehicle,” and then, the navigation device displays search results of “a sandwich bar near the vehicle.”
When the navigation device executes the local voice recognition process, and the user says “zoom-in” as an operation command for magnifying a map image, the navigation device recognizes the word of “zoom-in” as the operation command. Thus, the navigation device displays magnified map image. When the navigation device executes the center side voice recognition process, and the user says “zoom-in” as an operation command for magnifying a map image, the word of “zoom-in” may not be recognized. Instead, web sites may be searched with using the word “zoom-in” as a key word. This operation is the unintended operation for the user. Thus, the user is confused.